Witness information concerning the aircraft immediately before impact indicates that it was operating normally and under control while flying up the valley. As well, because the pilot had called the Fire Centre seven minutes before the occurrence and gave no indication that there was any problem with the flight or the aircraft, it is unlikely that mechanical defect contributed to this accident. After the radio call, however, it is possible that the crew observed the dust being raised by the motor-cycles in the valley and, suspecting that it was smoke from a forest fire, decided to carry out low-level reconnaissance before reporting the fire to the Fire Centre. In any event, the pilot flew up a valley that would likely have given him the illusion of there being a suitable exit route. Furthermore, because of the high outside air temperature and the high operating altitude above sea level, the aircraft performance was reduced, such that the available rate-of-climb was only sufficient to keep the aircraft at a near-constant height above the rising valley floor. It is likely that when the aircraft turned around the knoll, the pilot saw the mountain bowl, realized that the aircraft could not out-climb the steep walls of the bowl ahead, and decided to turn around. The combination of the flight path angle, reported by witnesses as being parallel to the rising valley floor, and the steep impact angle is characteristic of an aircraft that has stalled and struck the ground. When the aircraft entered the steep turn reported by the witnesses, the aircraft's stall speed would have increased; this airspeed would have now been higher than the suspected climb speed of about 105 mph, and, as a result, the aircraft would have stalled in the turn. The aircraft was reported to be 300 to 400 feet above the ground, and, in this situation, there would have been insufficient height for the pilot to recover from the stall before the aircraft struck the ground.Analysis Witness information concerning the aircraft immediately before impact indicates that it was operating normally and under control while flying up the valley. As well, because the pilot had called the Fire Centre seven minutes before the occurrence and gave no indication that there was any problem with the flight or the aircraft, it is unlikely that mechanical defect contributed to this accident. After the radio call, however, it is possible that the crew observed the dust being raised by the motor-cycles in the valley and, suspecting that it was smoke from a forest fire, decided to carry out low-level reconnaissance before reporting the fire to the Fire Centre. In any event, the pilot flew up a valley that would likely have given him the illusion of there being a suitable exit route. Furthermore, because of the high outside air temperature and the high operating altitude above sea level, the aircraft performance was reduced, such that the available rate-of-climb was only sufficient to keep the aircraft at a near-constant height above the rising valley floor. It is likely that when the aircraft turned around the knoll, the pilot saw the mountain bowl, realized that the aircraft could not out-climb the steep walls of the bowl ahead, and decided to turn around. The combination of the flight path angle, reported by witnesses as being parallel to the rising valley floor, and the steep impact angle is characteristic of an aircraft that has stalled and struck the ground. When the aircraft entered the steep turn reported by the witnesses, the aircraft's stall speed would have increased; this airspeed would have now been higher than the suspected climb speed of about 105 mph, and, as a result, the aircraft would have stalled in the turn. The aircraft was reported to be 300 to 400 feet above the ground, and, in this situation, there would have been insufficient height for the pilot to recover from the stall before the aircraft struck the ground. The pilot was certificated and qualified for the flight in accordance with existing regulations. There was nothing found to suggest any airframe failure or system malfunction had occurred either before or during the flight. The valley and surrounding terrain created an illusion that a suitable exit route existed at the end of the valley. The combination of high air temperature and altitude reduced aircraft climb performance. When the pilot entered a steep left turn to avoid the rising terrain, the stall speed increased; as a result, the aircraft stalled. When the aircraft stalled, its height above the ground was insufficient for the pilot to recover from the stall.Findings The pilot was certificated and qualified for the flight in accordance with existing regulations. There was nothing found to suggest any airframe failure or system malfunction had occurred either before or during the flight. The valley and surrounding terrain created an illusion that a suitable exit route existed at the end of the valley. The combination of high air temperature and altitude reduced aircraft climb performance. When the pilot entered a steep left turn to avoid the rising terrain, the stall speed increased; as a result, the aircraft stalled. When the aircraft stalled, its height above the ground was insufficient for the pilot to recover from the stall. While the pilot was manoeuvring to avoid rising terrain, the aircraft stalled at a height which was insufficient to allow him to effect a recovery. Contributing to the accident was the reduced aircraft climb performance and the illusion created by the features of the surrounding terrain.Causes and Contributing Factors While the pilot was manoeuvring to avoid rising terrain, the aircraft stalled at a height which was insufficient to allow him to effect a recovery. Contributing to the accident was the reduced aircraft climb performance and the illusion created by the features of the surrounding terrain.